(Associated Press)Washington's still trying to identify the man shown executed by Iraqi militants in a grainy video. His killers say it's Specialist Keith Matt Maupin. Defense officials are using audio and image-enhancing tools but still aren't sure. Maupin's hometown has been on edge since the Arab T-V station Al-Jazeera aired the video Monday. Technicians are looking for any clues that can help -- clothing worn, scars or birthmarks, jewelry and room where it was filmed. They also listen to the voices, dialect and exterior sound. That's how they identified the masked man who beheaded American civilian Nicholas Berg last month. Defense officials usually won't identify a victim until they have a body.